The present invention relates to a governor for an internal combustion engine and, more particularly, a floating-lever type governor for a diesel engine for an outboard motor.
Generally, outboard-motor internal combustion engines must meet the absolute requirement that they are comparatively light in weight and compact in structure, and conventionally internal combustion engines for use as an outboard motor predominantly comprised gasoline engines.
However, as the price of gasoline has been tremendously raised in recent years, it has been increasingly demanded that in place of a gasoline-type internal combustion engine with which the fuel cost is relatively high, the employment for an outboard motor should be made of a diesel engine with which the fuel cost is comparatively low. With diesel engines, however, the fuel injection control involves more of complexity than with gasoline engines. Besides, in the case of an outboard engine, acceleration and deceleration thereof should necessarily be effected by operating a steering handle disposed to project toward the bow of a ship or boat, and it forms an important requirement that the operation of the handle can be made with ease. Also, in most instances a diesel engine for an outboard motor is housed in a lower and an upper cowlings and it should be met, too, that an inspection operation and/or a maintenance work can be performed simply by removing away or opening the upper cowling.
Further, with conventional outboard diesel engines, it is operated in starting the engine to let fuel be injected about twice as much as the amount at the time of normal engine operation so that the ignition can take place without fail and also in order to rapidly raise the rotation number immediately after the engine has been started.
Then, for the purpose of controlling the engine speed by way of controlling the fuel injection, a governor is incorporated in the internal combustion engine. With conventional centrifugal-type governors, the motion of a governor spindle caused by centrifugal force exerted by a governor weight is transmitted through such as a floating lever, a link and so forth to a control rod for controlling the fuel injection to thereby automatically govern the engine speed. To increase the fuel injection at the starting of the engine, a handle provided separately of the governing or regulator handle is operated.
With the governor of such system, indispensably the arrangement and the operation have to be complex and, in addition, there lies the danger that the operation lever for increasing the fuel injection is in error operated during normal running of the engine, when the engine is caused to operate at a power above the prescribed value and becomes damaged.
In the case of floating-lever type governors in which the motion of the governor spindle caused by centrifugal force of the governor weight is transmitted to the control rod through such as a first lever, a floating lever and a link member and in which almost all of the force is born by the first lever so that no substantial portion of the force may not be transmitted to members following to the link, an idle spring is incorporated to control the rotation number during idling of the engine. The idle spring is imparted with a spring constant such that during idling rotation of the engine, a balancing takes place between the force of the idle spring and that of the governor, and as soon as the rotation number lowers below the idling rotation number, the fuel injection is increased, while when the rotation number tends to come above the idling rotation number, the fuel injection is suppressed.
Preferably, the idle spring should be located as far away the governor as possible: At each joint in the path of transmission of force to the control rod through such as governor spindle, first lever, floating lever, link member, further levers and pins and so forth, there exists an innegligible gap or play, and if the governor is operated in a state where force in a certain direction is not constantly applied to such link or joint portions, the operation of the governor becomes unstable at the link portions. Therefore, preferably it is to be made that the idle spring is provided at the side of the control rod so that force in a certain direction is constantly applied to the joint portions. At the same time, it may be required to adjust the spring force of the idle spring during the engine operation so as to set the rotation number of the engine idling, and the idle spring should necessarily be located at a position affording an access with ease.
Further, in the internal combustion engine for an outboard motor in which the control rod for controlling the fuel injection is provided so as to be movable parallel to a vertically arranged crankshaft, it is utmost preferred to mount a governor at an upper portion of the engine so that an easy access can be made for maintenance, inspection and adjustment operations. Thus, an idle-spring chamber in which to house the idle spring should preferably be disposed in an upper portion of the engine.
In conventional governors, there is included such a one which employs the so-called torque spring system in which compensation of the difference between the force of a governor weight and that of a regulator spring constituting the main spring is effected by the function of a torque spring so that when the engine rotation lowers below a certain value, the fuel injection can be increased. A fuel-injection increasing or controlling mechanism of such torque-spring system may not possibly be employed for a floating-lever type governor in which the force of a regulator spring is born by a first lever and the force born by this lever is almost in balance with the force of a governor weight and in which the force of the regulator spring is not transmitted to links and a lever for operating a control rod for controlling the fuel injection which are arranged downstream of a floating lever in the direction of the force transmission.